a) Field of the Invention
The present invention relates to a portable aerosol delivery apparatus that can be worn by a user requiring a pharmaceutical treatment. The present invention particularly relates to a wearable aerosol delivery apparatus whereby a dose of a pharmacologically active agent may be readily supplied to the user.
b) Description of the Prior Art
Aerosols are used for the delivery of a variety of substances, including perfumes, repellants and drugs. Examples of drugs that may be administered in an aerosolized form include anti-convulsant, anti-arrhythmic, hormonal, anti-diuretic, corticosteroid, anti-diabetic, immune suppressive, antihistamine and anti-asthmatic agents. Asthma, for example, is a chronic inflammatory respiratory disease that may be life-threatening. Asthma affects people in varying degrees, from mild, with occasional symptoms, such as during vigorous exercise, to severe with symptoms every day. During an asthma attack, shortness of breath occurs which is caused by inflammation and bronchoconstriction. The inflammation causes the inner-lining of the airways to swell and produce excessive amounts of a thick mucus, while the bronchoconstriction causes the smooth muscle wrapped around the airways to tighten, which causes the bronchial tubes to become narrow.
Asthma may be treated with preventer or reliever agents. Preventers such as steroids are topically active agents used to control the inflammation and counter moderate and severe asthma. Relievers such as beta-agonists are bronchodilating agents that relieve bronchospasm and open the airways. Relievers are a "first-aid" treatment for asthma attacks and must be available for instant use by the patient when symptoms occur.
Compared to the oral administration, the inhaled medication goes directly to the airways and relief occurs within 5 to 10 minutes, with systemic side effects being reduced since a smaller dose is needed.
The standard apparatus for the delivery of aerosol medication is a metered-dose aerosol inhaler (MDI). A conventional MDI comprises a body having a mouthpiece covered with a cap. The body has a receptacle into which a canister is inserted. The canister contains a reservoir of medication in admixture with a pressurized propellant and a fixed-volume metered-dose chamber.
The MDI is used as follows: The user removes the cap from the mouthpiece, holds the MDI upright and shakes it. The user tilts his or her head back, breathes out, opens his or her mouth and places the mouthpiece therein. The user actuates the MDI by manually pressing the canister down into the body of the MDI as he or she simultaneously inhales for 3 to 5 seconds. Upon actuation of the MDI, a metered dose of medication is released from the reservoir, captured in the chamber and released as an aerosol mist for inhalation by the user. The user then holds his or her breath for 10 seconds to allow the medication to reach deeply into the lungs.
A first problem with conventional MDIs is that the usage technique associated therewith is complex. Coordinating the actuation of the MDI with the start of the inhalation is hard to develop and one third of children using MDIs do not have a proper MDI usage technique. Even people with a good MDI technique experience difficulties during an acute attack, when the medication is most needed. In the best conditions, only approximately 10% of the released dose is deposited into the lungs.
A second problem with conventional MDIs resides in their bulkiness. The canister generally holds over 200 doses. However, a severe asthmatic requires an average of six doses daily. Consequently, a user may be carrying daily a full month's capacity of medication. It is also difficult to determine the amount of medication remaining in the canister. Patients must calculate the number of doses taken and write the information down on a calendar, which is cumbersome. Consequently, patients rarely count the doses taken and may be carrying an empty or almost empty canister. Moreover, the pressure in the canister has a tendency to decline, reducing the effectiveness before the number of doses specified by the manufacturer has been used, which may be a cause of asthmatic exacerbation. A third problem related to the canister is that once empty, it must be thrown away and replaced. This means that in order to be safe, a user must carry an inhaler apparatus containing a canister and a "spare" canister.
Another problem with conventional MDIs is that they cannot be conveniently carried by users, for example during physical activities such as jogging, cycling and swimming or during sport competitions. In these circumstances and in others, the user may not favor carrying the MDI in a pocket or in a separate handbag. The user may have to search for the MDI during an acute attack or lose it, which may give rise to a life-threatening situation.
A fifth problem with conventional MDIs is that the parts constituting the MDI, namely the plastic inhaler, the cap and the mouthpiece must be cleaned every day to avoid a clogging buildup of medication.
There exist metered-dose inhalers that are actuated by breath. For example, reference is made to U.S. Pat. Nos. 5,404,871 and 5,655,516 issued to Goodman et al. However, such inhalers are actuated by a patient's inspiratory effort. Such inhalers detect the patient's inspiratory inhalation and release one or more pulses of aerosol medication when a pre-selected delivery threshold is exceeded, or when a new delivery threshold based on a previously detected inspiratory inhalation not exceeding the prior delivery threshold is exceeded. Other breath-actuated metered-dose inhalers release a dose when the inspiratory effort moves a mechanical lever to trigger a release valve. Such inhalers are complicated, expensive to manufacture and remain bulky.
Devices are known which allow the carrying of an asthma inhaler in a holder that may be attached to the user. For example, reference is made to U.S. Pat. No. 5,730,118 issued to Hermanson and U.S. Pat. No. 5,779,122 to Martinelli. However, such devices remain bulky and conspicuous.
Devices in the form of a bracelet or a ring that carry substances such as repellants or fragrances are known. For example, reference is made to U.S. Pat. No. 4,061,249 issued to Smith, U.S. Pat. No. 4,241,850 to Speer, U.S. Pat. Nos. 4,972,684 and 5,217,143 to Aitken and U.S. Pat. No. 5,358,144 to Mock.
It would therefore be highly desirable to provide an aerosol delivery apparatus that would be conveniently worn on a user's body at all times.
It would further be highly desirable to provide an aerosol delivery apparatus that would facilitate the usage technique.
It would further be highly desirable to provide a filling mechanism for injecting a supply of the aerosol into the reservoir.